I'm in the process of installin a thru the wall system. I have a sellkirk theu the wall kit from Lowes and have ready the diredtions several times. That being said I have cut the hole out through the sheetrock, sheathing & vinal siding.... Know my question for you is when I mount that outter flange to the house should I remove the vinal siding so it will sit flush to the siding? Or is it ok to screw it over the siding? I think this will create a problem when I go to mount the wall support directly beneath this to support the t-joint. I believe that with the siding cut away everything will sit flush to the sheathing and make it much easier to keep plumb and will make everthing more secure to the structure, rather than trying to crush or sqwish the siding in...... Does this make sense? I hope someone can shed some light on this....need to get this done soon.....it's starting to get darn cold here in New Hampshire!!